1. Field of the Invention
This invention relates to distributors for spark ignited vehicle engines.
2. Prior Art
Radio noises generated by automobiles have caused interference to various types of communication equipment such as radios and televisions. The problem can be reduced by reducing the emission of such electromagnetic noise from the automobile. It has been known that the ignition distributor for automobiles is one of the main points where such noises generate. When a spark occurs between the rotor electrode and each of the stationary side electrodes, a jamming radio wave is emitted. However, no effective noise suppression device for the distributor has been developed yet. Among the known attempts to reduce noise has been the use of a resistor attached to an external terminal of the spark plug. A resistor can also be inserted in one position of the high tension cable. Further, a noise suppressing capacitor can be used.
Other attempts to reduce noise include shaping of the rotor to a sharp point so that arcing can occur with less emission of noise. It is also known to use silicon grease to reduce the electromagnetic emissions associated with arcing. Typically, the solutions have added to the cost of the distributor and have not provided a complete solution. These are some of the problems this invention overcomes.
U.S. Pat. No. 3,542,006 issued to Dusenberry et al discloses an RFI suppressing ignition system which combines a relatively large gap width between the rotating terminal and each stationary terminal with a television-radio radiation suppression ignition cable and resistor type spark plugs.
U.S. Pat. No. 3,600,530 also issued to Dusenberry et al provides an RFI shield comprising a generally cup-shaped metallic housing 130, 132 that is attached to the breaker plate of the distributor. The cup-shaped housing is formed in two complementary interfitting metallic parts shown in FIGS. 3, 4 and 5. The compartment defined by the breaker plate and the two housing shield parts encloses the distributor breaker contacts, a capacitor and a capacitor lead wire connecting a capacitor to one of the breaker contacts.
U.S. Pat. No. 4,039,787 issued to Hori et al discloses a distributor wherein there is provided a first discharging gap and a second discharging gap. The second discharging gap is closed to the first discharging gap and both of the first and second discharging are located between the electrodes of the distributor rotor and a stationary contact. The gap distance of the second discharging gap is shorter than the first discharging gap. It is believed that RFI due to the spark discharge between the rotor and the distributor cap contacts can be reduced by causing the discharge current to have a relatively large pulse width and relatively small current value.